Name a cyclic unsaturated carbon compound.

Benzene is an example of a cyclic unsaturated carbon compound. In benzene, six carbon atoms form a ring structure and there are three single and three double bonds between the carbon atoms. The structure of benzene is as follows:

Write the molecular formula of ethene and draw its electron dot structure.

Ethene is an unsaturated compound having double bond. The molecular formula of ethene is C 2 H 4 . Electron dot structure of ethene is:

3 mL of ethanol is taken in a test tube and warmed gently in a water bath. A 5 % solution of alkaline potassium permanganate is added first, drop by drop to this solution, then in excess. How is 5 % solution of KMnO 4 prepared? State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess? Write a chemical equation of this reaction.

To make 5 % of KMnO 4 solution, 5 g of KMnO 4 is to be added in water to make the final volume 100 mL . Alkaline potassium permanganate acts as an oxidising agent which provides a nascent oxygen to the alcohol and turns it into a carboxylic acid. When purple alkaline KMnO 4 is added drop by drop into ethanol, it reacts to give acetic acid and the purple colour of KMnO 4 disappears. When it is added in excess, the entire ethanol has been turned into acid and no more ethanol is left to react with alkaline KMnO 4 and the purple colour persists in the solution. Ethanol on reaction with alkaline KMnO 4 gets oxidised and forms ethanoic acid. Ethanoic acid is also known as acetic acid. The reaction between ethanol and alkaline KMnO 4 is as follows: C 2 H 5 OH ethanol → heat alkaline KMnO 4 CH 3 COOH ethanoic acid

What is a homologous series of carbon compounds ? Give an example and list its three characteristics.

A series of carbon compounds in which the same functional group substitutes the hydrogen atom is called a homologous series. A homologous series is a group of organic compounds having same functional group and similar chemical properties in which the successive compounds differ by CH 2 group. For example; the alkane series CH 4 , C 2 H 6 , C 3 H 8 , C 4 H 10 , etc. The list of characteristics is as follows: (i) All the members of a series can be represented by the same general formula. e.g. General formula for the alkane series is C n H 2 n + 2 . (ii) All the members of a homologous series can be represented by the same general formula. (iii) Any two adjacent homologues differ by 1 carbon atom and 2 hydrogen atoms in their molecular formulae.

Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound.

Cyclohexane is a saturated compound in which carbon atoms are arranged in a ring. There are total 6 C-C single bonds present in this compound. The structure of the compound is:

Why are most carbon compounds poor conductors of electricity?

Carbon forms covalent bonds. Covalent compounds are non-conductors of heat and electricity. This is because during the formation of covalent bonds, only electrons are shared between atoms and no charged particles are formed. Carbon forms four covalent connections using its four valence electrons, it rarely has any free electrons. Therefore, most carbon compounds are poor conductors of electricity.

A compound ‘ X ’ on heating with excess conc. sulphuric acid at 443 K gives an unsaturated compound ‘ Y ’. ‘ X ’ also reacts with sodium metal to evolve a colourless gas ‘ Z ’. Identify ‘ X ’, ‘ Y ’ and ‘ Z ’. Write the equation of the chemical reaction of formation of ‘ Y ’ and also write the role of sulphuric acid in the reaction.

Compound X is CH 3 CH 2 OH -ethanol, which on heating with concentrated sulphuric acid at 443 K gives ethene, which is an unsaturated compound. Ethanol reacts with sodium metal to produce sodium ethoxide and hydrogen gas ' Z '. CH 3 CH 2 OH + Na → CH 3 CH 2 ONa + H 2 Chemical reaction of formation of Y is, CH 3 CH 2 OH Ethanol → 443 K Conc . H 2 SO 4 CH 2 = CH 2 Ethene + H 2 O Here, concentrated sulphuric acid acts as a dehydrating agent, it removes water molecule from ethanol.